Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden of behavioral disclosure. It states the tool is a 'public profile lookup,' which implies read-only behavior and a limitation to public profiles. It also mentions the cost ('$0.05/call via x402') and lists the return fields. While it does not describe failure modes or auth requirements, it provides meaningful behavioral context beyond a generic lookup.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence that efficiently conveys the core function, supported platforms, returned data, and cost. Every phrase adds value with no redundancy, making it easy for an agent to parse quickly.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool is a simple 2-parameter lookup with no output schema, the description is largely complete: it specifies the platforms, the type of data returned, and the cost. Minor gaps include response format and exact platform parameter values, but these are not critical for a straightforward profile fetch. It is adequate for the tool's complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has zero descriptions, so the description must compensate. It does clarify that 'platform' likely accepts values like 'X' or 'LinkedIn' and that 'handle' is the profile username. However, it does not provide explicit parameter definitions, format examples, or constraints. The description adds some meaning (platform options, handle implication) but not comprehensive coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool performs 'X (Twitter) or LinkedIn public profile lookup' and lists the specific data points returned (name, bio, followers, company, experience). This distinguishes it from sibling tools like company_lookup, which focuses on companies. The verb 'lookup' and resource 'profile' are specific and unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the tool is for fetching public profiles on X/Twitter or LinkedIn by specifying these platforms and the data fields. It does not explicitly exclude alternatives or name a competing tool, but the context is clear enough that an agent would understand when to use it. No exclusions or alternative references are given, but the purpose is sufficiently distinct from siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.